Annulus gear and drive shell

ABSTRACT

A method of producing a torque transmission between a driving member and a driven member including the steps of capturing an annular gear within the interior of a hollow cylindrical shell formed of a formable material which is caused to be flow formed around a portion of the exterior of the gear to militate against any relative longitudinal and axial movement between the shell and the gear.

[0001] This application claims the benefit of U.S. Provisional PatentApplication Serial No. 60/361,993, filed Mar. 5, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a torque transmission system andmore particularly to an apparatus for transmitting torque between anannulus gear and a drive shell having a splined portion and a method forproducing the same.

[0004] 2. Description of the Prior Art

[0005] In planetary automatic transmission systems, torque istransmitted from component to component within the transmission.Frequently, these components are of complex design, permitting them toserve several functions and reduce the number of components in theassembly. In such a case, the material from which the component is madeis usually selected to accommodate the greatest stresses applied to thiscomplex component. A large portion of such a component is stronger andheavier than is really necessary for the application.

[0006] In order to reduce weight, aluminum is used in place of steelwhere possible. Aluminum is not an appropriate material for suchcomponents as annulus gears, but it can be used for drive shells whichtransmit the torque between annulus gears and other supporting ortorque-controlling structures within the transmission. A current versionof a system which the present invention can be applied uses an annulusgear with a drive spline on its face, an aluminum drive shell with abore to locate the annulus gear and pockets to receive the drive splineteeth, and a snap ring to retain the annulus gear within the aluminumdrive shell. The aluminum component is cast and is subject to theporosities and imbalance problems common to cast components.

[0007] It is an object of the present invention to produce a torquetransmission system which is light in weight and relatively inexpensiveto manufacture.

[0008] Another object of the invention is to produce a torquetransmission system including an annulus gear and an associated driveshell containing the gear which may be readily manufactured.

SUMMARY OF THE INVENTION

[0009] The above and other objects of the invention may be achieved bythe production of a torque transmission system between a driving memberand a driven member comprising the steps of:

[0010] providing a hollow cylindrical shell having spaced apart ends anda longitudinal axis;

[0011] forming a coaxial splined section adjacent one end of the shellfor engagement with one of the members to transmit torque therebetween;

[0012] placing an annulus gear with internal spines formed or cut on theinterior surface thereof coaxially within the hollow cylindrical shellbetween the spaced apart end thereof; and

[0013] capturing the annulus gear within the shell to enable torquetransmission between the gear and the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above objects and advantages of the invention will becomereadily apparent to those skilled in the art from reading the followingdetailed description of the invention when considered in the light ofthe accompanying drawings, in which:

[0015]FIG. 1 is a perspective view of a blank used to form the driveshell of the invention;

[0016]FIG. 2 is a perspective view of the annular gear to be integratedwith the blank illustrated in FIG. 1;

[0017]FIG. 3 is a perspective view of the forming rollers and mandrelused to form the finished torque transmission products; and

[0018]FIG. 4 is a sectional view of the completed torque transmissionproduct produced by the novel method of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] The torque transmission system of the invention is typicallyproduced by the following method wherein the first step includes theprovision of a blank 10 as illustrated in FIG. 1. The blank 10,sometimes referred to as a slug, is formed of a formable metal such as a6000 series aluminum of a thickness of eight to nine millimeter in thepreferred embodiment. The blank 10 is provided with a centrally formedaperture 12.

[0020]FIG. 2 illustrates an annular gear 14 is integral to the inventionas will become manifest hereinafter. The annular gear 14 is typicallyproduced from a steel stock material and is provided with internallyformed splines 16 which extend radially inwardly of the annulus. Theouter peripheral wall of the annulus is provided with outwardlyprojecting surface modifications 18.

[0021] In order to form an integral assembly of the blank 10 and theannulus gear 14, there is provided a rotating mandrel 20; illustrated inFIG. 3. The gear 14 is adapted to be received within a suitably formedshelf on the outer peripheral surface of the mandrel 20. The mandrel 20is typically provided with a clamping mechanism effective to hold theblank 10 on the mandrel end.

[0022] The outer peripheral surface of the mandrel 20 is provided with acontour necessary to effect the shape of the blank 10 into the desiredcompleted shape. More specifically, the one end of the mandrel 20adjacent the blank 10 is provided with an array of splines 22 whichproject outwardly. The other end of the mandrel 20 is contoured lugs 24.Intermediate the opposite end of the mandrel 20, the central portion isgenerally smooth with the exception of the gear receiving shelf alludedto earlier in the description.

[0023] After the blank 10 is suitably affixed to the one end of themandrel 20, an assembly of forming rollers 30 is caused to move axiallycausing the metal stock of the blank 10 to be formed in a generallycup-shape over the mandrel 20. Such relative movement between therotating mandrel 20 and the rotatable forming rollers 30 causes themetal of the blank 10 to flow and thereby conform to the contour of theouter surface of the mandrel 20. Simultaneously with the above action,the metal of the blank 10 flows over the one end to form outwardlyprojecting splines 32, and subsequently the material of the blank 10flows to capture the gear annulus 14 by flowing around the surfacemodification 18 formed on the outer peripheral surface of the gearcausing the gear annulus to be tightly captured and refrained from anyrelative movement with the outer shell being flow formed by theinteraction between the rotating mandrel 20 and the forming rollers 30.

[0024] Finally, the circumferentially outermost marginal portion of theblank 10 is caused to flow into and around the lugs 24 on the mandrel 20to form the illustrated locking lug configuration 34 on the completedpart for receiving a cover, for example, for the end of a driving shaft,the extreme end of which has externally projecting splines adapted toengage with the internally projecting splines 16 of the captured gear14.

[0025] It will be understood that the assembly of the forming rollers 30is adapted to move axially of the mandrel 20 until the blank 10 isformed into a completed part. During the relative movement of themandrel 20 and the blank 10, and the assembly of forming rollers 30, thethickness of the metal of the blank 10 is reduced as much as twenty-fivepercent (25%).

[0026] The cooperation between the inner surface of the formed blank 10and the radially outwardly projecting surface modifications 18 providethe ability of the system to transmit torque between the formed blank 10and the annulus gear 14.

[0027] It will be appreciated that the flow forming of the material ofthe blank 10 along the outer surface of the annulus gear 14 adequatelyretains the gear 14 from any relative rotation movement in respect ofthe shell 12 as well as militates against relative axial movementtherebetween. Such structure thereby eliminates the necessity of aretaining ring, for example, and results in a reduction of cost ofmaterials, as well as the cost of machining.

[0028] It has been discovered that aluminum is the preferred metal forforming the drive shell 12.

[0029] In accordance with the provisions of the patent statutes, thepresent invention has been described in what is considered to representits preferred embodiment. However, it should be understood that theinvention can be practiced otherwise than as specifically illustratedand described without departing from its spirit or scope.

What is claimed is:
 1. A method of producing a torque transmissionsystem between a driving member and a driven member comprising the stepsof: 1) providing a hollow cylindrical shell having spaced apart ends anda longitudinal axis; 2) forming a coaxial splined sector adjacent oneend of the shell for engagement with one of the members to transmittorque therebetween; 3) placing an annular gear with internal splinesformed on the interior surface thereof coaxially within the hollowcylindrical shell between the spaced apart ends thereof; and 4)capturing the annular gear within the shell to enable torquetransmission between the gear and the other one of the members.
 2. Themethod defined in claim 1 wherein the shell provided in step 1) is offormable metal stock.
 3. The method defined in claim 2 wherein step 4)includes the flow forming of the shell around the annular gear.
 4. Amethod of producing an annulus gear and drive shell assembly comprisingthe steps of: 1) providing an annular blank of sheet metal stock havingtwo spaced apart surfaces and an aperture formed centrally thereof andextending between the surfaces; 2) providing a mandrel having alongitudinal axis and an outer peripheral surface configured toselectively secure an annulus gear thereto; 3) positioning an annulargear on the outer peripheral surface of the mandrel; 4) attaching theannular blank to the mandrel; 5) providing at least one forming rollerassembly; 6) causing the forming roller assembly and the mandrel torotate relative to one another; 7) effecting relative longitudinal andtranslatory movement of the forming roller assembly and the mandrelcausing the forming roller assembly to contact one surface of theannular blank and forcing the other surface to contact the blank to flowaround the annular gear to capture the same onto the formed blank; 8)continuing the relative rotational and translatory movement between theforming roller assembly and the mandrel until the blank has become acup-shaped drive shell; and 9) withdrawing the cup-shaped drive shelland the integral annular gear from the forming roller assembly and themandrel.
 5. An annulus gear and drive shell product for transmittingtorque between a driving member and a driven member comprising: a driveshell formed of a formable metal having a longitudinal axis, and acylindrical body with spaced apart coaxial ends, one of the ends adaptedto be coupled to a driving member and the other end adapted to becoupled to a driven member; and an annular gear disposed coaxiallywithin the interior of the cylindrical body and retained therein by flowformed portions of the metal of the cylindrical body of said driveshell.
 6. The produced defined in claim 5 wherein said annular gear isprovided with radially inwardly projecting splines.
 7. The productdefined in claim 6 wherein said annular gear is provided with radiallyoutwardly projecting surface modifications.
 8. The product defined inclaim 5 wherein the formable metal of said drive shell is aluminum. 9.The product defined in claim 5 wherein the formable metal of said driveshell is steel.